Improvement in automatic relief-valves



L. D. SHAW.

Automatic Relief-Valve.

-2 Sheets--Sheet 2.

Patented-1an.26,1875.

able in the smaller cylinder a.

UNITED STATES PATENT OFFICE.

LORING D. SHAW, OF BOSTON, MASSACHUSETTS.

IMPROVEMENT IN AUTOMATIC RELIEF-VALVES.

Specification forming part of Letters Patent No. 159,045. dated January 26, 1875 application tiled August 10, 1874.

To all Iwhom it may concern:

Be it known that I, LORING D. SHAW, of Boston, in the county of Suifolk and State of Massachusetts, have invented certain new and y preventing the bursting of nre-engine hose if the pressure is suddenly increased therein, as is constantly the case it' the valve or cut-olil at the nozzle is closed before the pump is stopped from workin g. This, my invention, is also very useful for other purposes besides the above named.

My invention consists in the combination, with a cylinder in which two different size pistons attached to a piston-rod are movable, of a valve-cylinder provided with two entrances to the said cylinder; a double-acting valve that is forced onto its seat by a pair of adjustable spiral springs. A return-pipe leads from the aforesaid valve-cylinder to the suction-pipe of the pump, through which the liquid escapes from the upper part of the cylinder as soon as the pressure in the hose-pipe falls below the standard pressure at which the valve is regulated to open.

0n the drawings, Figure l represents a ground plan of my invention. Fig. 2A represents a sidep elevation. Fig. 3 represents an end elevation. Fig. 4 represents a longitudinal section on the line A B, shown in Fig. l, and Fig. 5 represents a longitudinal section on the line C D, also shown in Fig. l.

Similar letters refer to similar parts wherever they occur on the drawings.

a represents the cylinder, the lower part, a', of which is reduced in diameter, as shown in Figs. 4 and 5. A piston, b, is movable in the cylinder a, and provided with a piston-rod, c, by means of which the piston b is connected to a secondary smaller piston, d, that is mov- From the cylinder a, and at a place between the pistons b and d, leads a pipe, c, to the pipe chamber or nozzle, in which the pressure is to be automatically regulated. This said pipe e may be connected directly to the delivery-pipe of the pump, or at some suitable pla-ce between the delivery-pipe of the pump and the valve or cut-olf on the nozzle of a fire-engine hose. From the smaller cylinder, c', leads a pipe or opening, j', to the suction-pipe of the pump, which opening is closed by the pistond when the latter is in its highest position. A va'lvecylinder, g, is located in close proximity to the larger cylinder, ai, and is provided with two openings, h and i, one below and the other above the piston b, by which communication is established between the pressure-pipe e, cylinder a, and valve-cylinder g. In the valvecylinder g is the valve 7c, movable up and down in a vertical direction, and is held onto its seat in the valve-cylinder g by means of a pair of spiral springs, Z l, cross-bars m n, and a regulating-screw, o, as shown in Fig. 3. The crossba-r u is provided with an index, p, by means of which and a graduated scale, q, the pressure on the valve k from the springs ll can be adjusted so that the said valve k will open at any desired pressure. The valve k is provided with two openings, viz., one, 1', through which the liquid can iioW from the cylinder a, opening h, and valve-cylinder g, through the opening t', into the space above the piston b, when the pressure in the hose exceeds that for which the valve k is regulated. As soon as the liquid is forced above the piston b it moves the said piston downward, and in so doing the pistonA d is forced by the openingf, thereby allowing the liquid in the force-pipe e to return through the cylinder a c and pipe f to the suction part of the pump, by which the extra pressure is reduced, and when the pressure is reduced to that of the springs l Z the valve la is forced onto its seat, and the pistons b and d are forced upward by the pressure of the liquid from the pipe c. As the pistons b and d rise upward the suction-pipe f is closed by the lower piston, d, and the liquid above the piston b is forced out through the opening t', the diametrical opening s in the valve k, and the returnpipe t to the suction-pipe f. The suction in the pipe f tends to create a vacuum in the upper` The combination, with the cylinders a a and Y their pistons b d and openin gs e f, of the Valvecylinder g, its openings h t', and double-acting Valve 7c, With its openings 1 s, and the returnpipe t to the suction-pipe, as and for the purpose set forth and described.

In testimony that I claim theforegoing as my own invention I have affixed my signature in presence of two Witnesses.

LORING D. SHAW. Witnesses:

ALBAN ANDRN, JOHN R. HEARD. 

